Which of the following statements is incorrect about photosynthesis ?

Options

A. Increases in incident light beyond a point increases formation of chlorophyll and thus increase in photosynthesis .
B. At high light intensities , both `C_3 and C_4` plants show increase in the rates of photosynthesis.
C. `C_3` plants respond to higher `CO_2` concentration by showing increased rates of photosynthesis leading to higher productivity has been used for some greenhouse crops such as tomatoes and bell pepper.
D. Tropical plant have a higher temperature optimum than the plants adapted to temperature climates.

Answer

To determine which statement about photosynthesis is incorrect, let's analyze each option provided.

### Step 1: Analyze the first statement
- **Statement:** "Increase in the incident light beyond a point increases formation of chlorophyll and thus increases photosynthesis."
- **Analysis:** This statement is incorrect. While light is essential for photosynthesis, excessive light can lead to photoinhibition, which can damage chlorophyll and decrease the rate of photosynthesis. Therefore, this statement is indeed incorrect.

### Step 2: Analyze the second statement
- **Statement:** "At high intensities of light, both C3 and C4 plants show an increase in the rate of photosynthesis."
- **Analysis:** This statement is correct. Both C3 and C4 plants can increase their rate of photosynthesis with higher light intensity, although C4 plants generally have a higher efficiency in utilizing light.

### Step 3: Analyze the third statement
- **Statement:** "C3 plants respond to higher carbon dioxide concentration by showing increased photosynthesis, leading to higher productivity, which has been used for some greenhouse crops such as tomatoes and bell peppers."
- **Analysis:** This statement is also correct. C3 plants do benefit from increased carbon dioxide levels, which enhances their photosynthetic rate, and this principle is applied in greenhouse cultivation.

### Step 4: Analyze the fourth statement
- **Statement:** "Tropical plants have a higher temperature optimum than the plants adapted to temperate climates."
- **Analysis:** This statement is correct. Tropical plants are adapted to higher temperatures compared to those in temperate climates, which have a lower temperature optimum.

### Conclusion
Based on the analysis, the incorrect statement about photosynthesis is the first one.

**Final Answer:** The incorrect statement about photosynthesis is the first one.

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